VASODILATOR EFFECT OF ADRENOMEDULLIN AND CALCITONIN-GENE-RELATED PEPTIDE RECEPTORS IN RAT MESENTERIC VASCULAR BEDS

The effect of adrenomedullin, a novel peptide of 52 amino acids, on vascular tone was investigated in the perfused rat mesenteric vascular bed. In the vasculature contracted with methoxamine, perfusion of adrenomedullin (10-11-10-7 M) caused a concentration-dependent decrease in perfusion ressure due to vasodilation. Additionally, a bolus infusion of adrenomedullin (300 and 500 pmol) produced a long-lasting vasodilator response, which was not affected in the presence of atropine (10-7 M) and propranolol (10-7 M). However, this response was inhibited in the presence of CGRP[8-37] (10-6 M), an antagonist for CGRP receptor. These results suggest that adrenomedullin induces nonadrenergic and noncholinergic vasodilation in which CGRP receptors may be involved. © 1993 Academic Press, Inc.